1. Field of the Invention
The present invention relates to a disk drive, and more particularly, to a suspension assembly having an end-tab, a stiffness of which is reinforced, and an actuator for a disk drive adopting the same.
2. Description of the Related Art 
As an information storage device of computer, a hard disk drive (HDD) is a device to reproduce/record data from/on disk using a read/write head.
Such a hard disk drive includes an actuator moving a read/write head to a predetermined position of a disk. The actuator is provided with: a swing arm; a suspension assembly installed in one end portion of the swing arm to elastically bias a slider toward a surface of the disk, the read/write head being mounted on the slider; and a voice coil motor (VCM) rotating the swing arm.
If the hard disk drive is powered on and the disk starts to rotate, the voice mail motor rotates the swing arm to move the slider over a recording surface of the disk. The read/write head mounted on the slider functions to reproduce and/or record data from/on the recording surface of the disk.
If the hard disk drive does not operate, that is, if the disk is stopped, the voice coil motor moves and parks the read/write head outside of the recording surface of the disk, to prevent the read/write head from colliding against the recording surface of the disk. Generally, such head parking systems can be classified into a contact start stop (CSS) system and a ramp loading system. In the CSS system, a parking zone in which data is non-recordable is provided in an inner circumference of the disk, and the head is parked in contact with the parking zone. In the ramp loading system, a ramp is installed outside the disk, and the head is parked on the ramp.
FIG. 1A is a perspective view showing a conventional suspension assembly of an actuator for a disk drive, FIG. 1B is a side view of the conventional suspension assembly of FIG. 1A, and FIG. 1C is a plan view showing the case when an end-tab is in contact with a front end portion of a ramp in the conventional suspension assembly.
Referring to FIGS. 1A and 1B, the suspension assembly 40 of the actuator includes a load beam 41 coupled to one end portion of a swing arm 32, and a flexure 44 supporting a slider 45 on which a head is mounted. A rear end portion of the flexure 44 is fixed to one surface of the load beam 41, that is, a surface facing a disk 20, by a welding or the like. A front end portion of the flexure 44 is freely movable. A limiter 47 limiting a pitching movement of the flexure 44 is provided between the front end portion and rear end portion of the flexure 44. The limiter 47 is extended through an aperture 46 that is positioned on the load beam 41. A dimple 43 protruded toward the flexure 44 is positioned on the load beam 41. A predetermined elastic force is induced to the flexure 44 by the dimple 43. In such a structure, the flexure 44 is freely movable, and thus the slider 45 attached to the flexure 44 can move freely in rolling and pitching directions.
As is described above, a ramp 50 is installed outside the disk 20 to park the head. An end-tab 42 is extendedly positioned on a front end portion of the load beam 41 and supported in contact with a surface of the ramp 50 when parking the head. A front end portion of the ramp 50 is inclined and overlapped with an edge portion of the disk 20 by a predetermined width, such that the end-tab 42 can be loaded and unloaded smoothly.
If the disk drive is powered off, the end-tab 42 is unloaded onto the ramp 50 from the disk 20. At this time, the end-tab 42 lifts up in contact with the inclined surface of the front end portion of the ramp 50. If the end-tab 42 lifts up above a predetermined height, the flexure 44, to which the slider 45 is attached, is separated from the dimple 43 due to an absorptive power between the slider 45 and the disk 20. In addition, a rotation speed of the disk 20 is reduced due to a power-off of the disk drive, and a lifted height of the slider 45 is also reduced.
If the lifted height of the slider 45 is reduced continuously, the head mounted on the slider 45 collides against the disk 20, causing the head and/or the disk 20 to be damaged. It is the limiter 47 that functions to prevent such an occurrence. In other words, when the end-tab 42 lifts up in contact with the inclined surface of the front end portion of the ramp 50, the limiter 47 engages the load beam 41, thereby preventing the lifted height of the slider 45 from being lowered below a predetermined height.
But when the end-tab 42 lifts up in contact with the inclined surface of the front end portion of the ramp 50, a considerable load is applied to the end-tab 42. If stiffness of the end-tab 42 is low, a connecting portion between the load beam 41 and the end-tab 42 may be deflected. If this phenomenon occurs, the limiter 47 cannot perform its own function, such that the head and/or the disk 20 may be damaged due to a collision. Since the slider 45 attached to the flexure 44 is not rapidly separated from the surface of the disk 20, it takes a long time to unload the end-tab 42, thereby degrading performance of the disk drive. In addition, if this phenomenon occurs repeatedly over time, the end-tab 42 may deform due to a fatigue phenomenon.
To overcome the above problems, stiffness of the end-tab needs to be increased. For this purpose, the end-tab may be formed large or thick. In this case, weight of the end-tab increases so that a driving performance of the actuator is degraded. Accordingly, there is demanded an end-tab which is relatively small and lightweight and has high stiffness.
Referring to FIG. 1C, when parking the head, to unload the end-tab 42 onto the ramp 50 before the slider 45 is rotated outside a perimeter of the disk 20, the ramp 50 is installed to overlap the front end portion of the ramp 50 with the edge portion of the disk 20 by a predetermined width D.
The conventional end-tab 42, however, is extended from the front end portion of the load beam 41 along a central axis of the load beam 41. Thus, the overlapped width D between the ramp 50 and the disk 20 is relatively wide, and a data storage space of the disk 20 is accordingly reduced. In addition, when stiffness of the end-tab 42 is low, it takes a long time to unload the end-tab 42. As a result, the overlapped width D between the ramp 50 and the disk 20 must be widened.
In FIGS. 2A through 2C, there is shown a suspension assembly having a longitudinally reinforced end-tab, which is disclosed in U.S. Pat. No. 6,181,529.
Referring to FIGS. 2A through 2C, an end-tab 71 is extendedly positioned on a front end portion of a load beam 58 of a suspension assembly in a longitudinal direction of the load beam 58. A slider 72 is attached to a flexure 75. Longitudinal channels 84 and 93 are positioned on the end-tab 71 along a longitudinal central axis of the end-tab 71. These longitudinal channels 84 and 93 cause stiffness of the end-tab 71 to be increased. In the conventional suspension assembly of FIGS. 2A through 2C, with stiffness of the end-tab 71 being increased, possibility of collision between the end-tab 71 and a disk in the parking of the head is reduced and the end-tab 71 can be unloaded more rapidly.
In the parking of the head, the end-tab 71 encounters a force in a horizontal direction when the end-tab 71 contacts with the front end portion of the ramp, as well as a force in a vertical direction due to the ramp. Seen from the shape of the end-tab 71, stiffness of the conventional end-tab 71 is relatively high in a vertical direction but not sufficiently high in a horizontal direction.
Since the end-tab 71 is extended from the front end portion of the load beam 58 in the longitudinal direction along the central axis of the load beam 58, an overlapped width between the ramp and the disk is relatively wide and thus the data storage space of the disk is reduced.
Compared with the end-tab of FIG. 1A, the end-tab of FIGS. 2A through 2C has an effect that increases the vertical stiffness, but does not have a satisfactory effect in the horizontal stiffness and the overlapped width between the ramp and the disk.
Meanwhile, Japanese Patent Laid-Open Publication No. 1999-306704 discloses an end-tab, which is extended from a front end portion of a load beam in an intersecting direction with respect to a central axis of the load beam. This end-tab has an advantage in that an overlapped width between the ramp and the disk is reduced, but has a disadvantage in that stiffness of the end-tab is insufficient and a twist deformation occurs.
As higher data recording density is demanded, overlapped width between the ramp and the disk needs to be reduced to widen the data recording surface of the disk. To load/unload the end-tab more rapidly, it is necessary to develop an end-tab having higher stiffness.